Wikipedia:Reference desk/Archives/Science/2008 November 3

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November 3

causes of high ferritin

Hello,

In case of a very high ferritin value (900+) for a long period of time (year+),not due to iron overload (ruled out by transferrin/iron), is there a list of possible diseases? I understand high ferritin+ESR+CRP is a "nonspecific inflammation", but is there a protocol for treating this? Mathityahu (talk) 00:34, 3 November 2008 (UTC)

No. Longstanding elevated ferritin in the absence of hemochromatosis is a marker of a chronic disease. The health carers would aim to diagnose and treat the underlying disease. Axl ¤ [Talk] 07:27, 3 November 2008 (UTC)

Biological Condition of Not Being Able to Sing

I once read, while studying for my music degree, that there is a rare condition that precludes an individual from the ability to sing. I cannot recall the name of that condition and would like to know what it is so that I can research it and learn more. I believe, for the most part, that if you can talk you can sing and would like to research this "rare condition" further. My clouded memory gives me the word "amesia" for the, but I cannot find that word in Wikipedia or any other dictionary that I have checked, so assume it is probably not the correct word. Does anyone know more? I have hit a dead end in my research on the web.Kschwacog (talk) 01:18, 3 November 2008 (UTC)

Amusia?--Lenticel ^(talk) 01:39, 3 November 2008 (UTC)

Note that amusia is an inability to mentally process music, not really a physical problem with the voice that precludes the ability to sing. Being monotone could be a result of amusia (the person can't hear notes, so doesn't produce them). It is also a result of lack of voice control - with many possible causes. A rather famous example is Julie Andrews. After throat surgery, she claimed to have lost the ability to sing. -- kainaw™ 03:09, 3 November 2008 (UTC)

<meow>You can't lose what you never had.</meow> —Angr 09:53, 3 November 2008 (UTC)

We are not amused. Edison (talk) 03:46, 3 November 2008 (UTC)

I was half expecting that the one-word answer to "not being able to sing" would be "Franamax". In fact, I'd propose it as an alternate definition... Franamax (talk) 07:46, 3 November 2008 (UTC)

Franamax has raised the issue of someone who knowingly can't sing (taking you at your word here). Does an "amusia" type realise the problem, ie, can hear music but can't sing it? Hope you know what i mean. Sorry Kainaw, you got it and variations. Julia Rossi (talk) 10:32, 3 November 2008 (UTC)

Stephen Fry has written that, although he can hear music vividly in his mind, when he tries to sing nothing comes out. You might ask him ;) —Tamfang (talk) 17:04, 3 November 2008 (UTC)

Our article on Tone deafness notes, "Being tone deaf is having difficulty or being unable to correctly hear relative differences between notes; however, in common usage, it refers to a person's inability to reproduce them accurately. The latter inability is most often caused by lack of musical training or education and not actual tone deafness." In colloquial usage, the inability to reproduce musical tones is often called "tone deafness"; though this colloquial usage is generally unrelated to the real medical condition called amusia. --Jayron32.talk.contribs 17:14, 3 November 2008 (UTC)

'Intensity' of dreams

Why is it that dreams are far more intense/realistic/emotional than real life? ie why can you experience far more pleasure/fear/happiness in dreams than in waking life?--GreenSpigot (talk) 02:26, 3 November 2008 (UTC)

Perhaps because your "dream senses" are not distracted by external stimuli so they are completely devoted to the sensations that your dream provides. Besides, the suspension of disbelief is over the top in dreams unless you learn how to snap out of it.--Lenticel ^(talk) 02:57, 3 November 2008 (UTC)

(edcon)For some of us, it's the opposite though this[1] in the article says anxiety is a common feature of dreams. That could also depend on age and development, and personality. Julia Rossi (talk) 03:00, 3 November 2008 (UTC)

It is not a given or accepted conclusion that dreams are in fact more intense, realistic, or emotional than real life. In the rare cases when dreams are remembered in detail, they may be related to the day's actual experiences, as those experiences are related to previous experiences and desires. Edison (talk) 03:46, 3 November 2008 (UTC)

I haven't remembered a dream in quite a few years, and even the one I did remember then was quite prosaic and uninteresting. So I'd have to dispute your assumption, maybe for some they are bright and vivid but for others they aren't. Dmcq (talk) 13:03, 4 November 2008 (UTC)

cognitive power of a feline

a domesticated cat sees a kitchen counter. It knows to get on that counter it must jump. Once the cat is on the counter can it determine that BECAUSE it jumped it is on the counter? Thanks, 32.149.68.21 (talk) 03:16, 3 November 2008 (UTC)

Clearly. Edison (talk) 03:43, 3 November 2008 (UTC)

My cat won't jump on the counter normally. However, if he smells ham, he jumps on the counter and eats the ham (until required to stop). I'm not able to say whether he KNOWS he is on the counter BECAUSE he knows he jumped or BECAUSE he knows he is now able to eat the ham. He certainly know that jumping on the counter is a prerequisite to eating ham. CBHA (talk) 04:28, 3 November 2008 (UTC)

The question is unanswerable, because we have no way to "see" into a cat's cognitive processes. What allows us to understand what Humans are thinking is that they can tell us. Language allows one to describe ones own thought processes. As yet, no cat has ever explained their behavior to us... --Jayron32.talk.contribs 13:29, 3 November 2008 (UTC)

The real question is why my cat keeps drinking the dirty water out of my dishes in the sink, when he's got a nice bowl of clean water next to his food? -- MacAddct1984 ^{(talk &#149; contribs)} 15:32, 3 November 2008 (UTC)

Oh, that's easy. "Wild" water that you find always tastes better than the domesticated water your human puts out for you. Every cat knows that. —Angr 15:42, 3 November 2008 (UTC)

yeah, cats prefer yucky water. i also find that the more disgusting their cat food is, the more they like it. Gzuckier (talk) 17:09, 3 November 2008 (UTC)

Seeing my black cat curled up on a black blanket, I wonder whether anyone has experimented to see whether cats are aware of their own color and the availability of camouflage, e.g. by letting black cats and white cats choose favorite spots in a room whose walls and floor are half white and half black. —Tamfang (talk) 17:15, 3 November 2008 (UTC)

That's strange. The cats I've had usually prefer spots where they are the least camouflaged, so that the hair they leave behind is maximally visible. In other words, black cats should prefer white sofas and rugs, and vice versa. —Angr 18:42, 3 November 2008 (UTC)

Yes - but that's just their natural tendency to wish to modify their environment. Rolling around on a white rug while shedding fur is a sure way to convert the annoyingly contrasty rug into something that's a PERFECT match for one's own fur - and therefore a great place to be camoflaged. SteveBaker (talk) 18:58, 3 November 2008 (UTC)

Or it could be that they are "marking their territory" which would show a preference for non-camoflaged backgrounds... The better the contrast, the more their fur is likely to stand out, and announce to the world "This is my territory, and all the females you find here belong to ME". That could be a good genetic survival strategy in and of itself, no? --Jayron32.talk.contribs 06:00, 4 November 2008 (UTC)

I'll put a white blanket on my bed and see what happens. —Tamfang (talk) 03:08, 4 November 2008 (UTC)

You'll have to put a black blanket on as well (if there isn't one already), to eliminate the fact that your cat just prefers the blanket instead of the bed. -- MacAddct1984 ^{(talk &#149; contribs)} 18:25, 4 November 2008 (UTC)

You'll need to blindfold yourself when you put the two blankets out or this won't be a double-blind experiment. The cat can't be allowed to know that you'd much prefer it to sleep on the dark blanket. SteveBaker (talk) 20:43, 4 November 2008 (UTC)

I can fold the blankets so that the bed is half-and-half; but it's trickier to arrange things so that he has a choice on the foot of the bed, his favorite spot. —Tamfang (talk) 17:19, 5 November 2008 (UTC)

Lizard Question

Do lizards lay eggs from which baby lizards hatch, or do lizards give birth to live babies, or do some approach the question of reproduction one way and some the other? CBHA (talk) 03:44, 3 November 2008 (UTC)

As far as I know, most lizards are oviparous, or egg-laying. There may be some ovoviviparous or viviparous lizards, but I can't think of any.66.57.219.148 (talk) 04:17, 3 November 2008 (UTC)

The Viviparous lizard seems to be the exception, though they are not exclusively viviparous. - Nunh-huh 04:20, 3 November 2008 (UTC)

Thank you. I was under the impression that ALL lizards laid eggs, until I was startled to read the article about the Western Blue-tongued Lizard.

"There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."

CBHA (talk) 04:39, 3 November 2008 (UTC)

How many video game references can you find in the Arecibo message?

How many video game references can you find in the Arecibo message? In the middle, there's a blue and white guitar from Guitar Hero. Below that is the human in Berzerk. Finally, at the bottom is one of the space invaders. 67.184.14.87 (talk) 04:15, 3 November 2008 (UTC)

The red dude who has fallen into a hole in the white platform is from Lode Runner--that makes it only 10 years impossible to be what it actually represents instead of 30:) DMacks (talk) 05:35, 3 November 2008 (UTC)

Oops, thought we were still talking about Guitar Hero, not Berzerk...completely forgot about that game! DMacks (talk) 05:50, 3 November 2008 (UTC)

charging objects..

I have been given an assignment. 8 point electrical charges are placed at the corners of a cube and another point electrical charge is placed at the centre of the sphere. I have to experimentally show that the 9th electric charge will not be in stable equilibrium. I have a theoretical explanation for that using Gauss's law. To do it experimentally, I thought I will use charged (conducting)spheres as point charges. I can charge a sphere using induction method. Is there any other way to charge a sphere?Please help. Also, suggest some ways to place the spheres at the corners of a cube. —Preceding unsigned comment added by 210.212.187.69 (talk) 04:28, 3 November 2008 (UTC)

without having the gumption to work on it, my instinct is to start with 1/rsquared being countered by the cosine of the angle between the middle point and the corner point and the middle point and the center of the side. i have no idea whether that will get you the right answer or even in the general direction of the right answer. Gzuckier (talk) 17:13, 3 November 2008 (UTC)

He/she has already solved the theoretical problem—the question is about actually doing the experiment. -- BenRG (talk) 21:18, 3 November 2008 (UTC)

Ahh, you're talking about electrical charges. When the original question opened with setting charges at the corners of a cube, I thought y'all were trying to blast your way into a vault or something. (How can the charge in the center of the sphere be unstable if you're going to blow the whole thing to smithereens anyway.....)

Good thing I wasn't the first person to try to reply! --DaHorsesMouth (talk) 23:08, 3 November 2008 (UTC)

Ah, yes, like the rapid detonation of charges Geraldo Rivera used to try and open up Al Capone's vault in 1986. Edison (talk) 04:06, 4 November 2008 (UTC)

DNA

Can DNA be seen in a microscope? ~DahiJynnuByzzuf~ —Preceding unsigned comment added by DahiJynnuByzzuf (talk • contribs) 06:07, 3 November 2008 (UTC)

This will sound weird, but what do you mean by "seen"? You can see DNA with the naked eye if you have enough, but it would just be some whitish goo. On the chromosome article, you can see a micrograph of chromosomes, which we know are each a double strand (essentially 2 molecules of DNA, with some other structural components) but all you can see is their overall shape. To see evidence of the helix or base-pairs, I think you'd need X-ray crystallography or a similar "not direct visualization" technique. DMacks (talk) 06:14, 3 November 2008 (UTC)

Let me rephrase it, are there microscopes that can magnify until the DNA looks like the way it's pictured in illustrations? DahiJynnuByzzuf (talk •

Again, it depends how detailed an illustration you mean (sort-of-elongated-thing, helix, ladder-rungs, actual sugars and bases and atoms, etc.). If you mean a specific type, would be helpful for us to be able to see "what you really mean" specifically (maybe a URL or image from a wikipedia page?). See above where I gave several answers for several levels of detail. DMacks (talk) 09:30, 3 November 2008 (UTC)

Okay, let me try this. Does DNA look like a ladder under the microscope? DahiJynnuByzzuf (talk —Preceding unsigned comment added by 75.110.204.225 (talk) 09:38, 3 November 2008 (UTC)

Hasn't Dmacks already answered that question in the first post? The answer is no Nil Einne (talk) 11:00, 3 November 2008 (UTC)

No, but the second best thing, seeing the chromosomes as they'r commonly depicted in textbooks, is sortof possible. See picture.EverGreg (talk) 12:13, 3 November 2008 (UTC)

Mitosis of a cell. The blue strings are chromosomes. Probably pictured using confocal microscopy or some other Fluorescence microscope.

Editors may be interested in checking out this user's contribs [2] Nil Einne [3] [4] [5]. Also as an anon [6] [7] Nil Einne (talk) 12:39, 3 November 2008 (UTC)

This may belong at Wikipedia:Administrator intervention against vandalism but is utterly unrelated to a perfectly legitimate question. EverGreg (talk) 13:30, 3 November 2008 (UTC)

Discussion moved to WT:RD Nil Einne (talk) 14:06, 3 November 2008 (UTC)

An ordinary light microscope can't possibly 'see' things that are smaller than roughly the wavelength of the light they are using...which is around 500 nanometers. A DNA molecule is around 2 nanometers wide - each "rung" in the ladder is only 0.2 nanometers long - but there are 200 million of them in just one chromosome. So an entire chromosome is 200,000 nanometers long - but only 2 nanometers wide. So clearly, you can't see the molecule as a little twisted ladder in a light microscope - but DNA molecules are twisted and coiled many times over - so an entire DNA molecule ought to be just about visible in the best light microscope you could imagine. However, in a 'typical' light microscope - you won't see a thing.

A 'transmission' electron microscope (TEM) uses teeny-tiny electrons instead of big fat light waves - so a really good one can just about see things about 1 nanometer across. Most are not that good. So even in the best TEM won't see enough detail to see a spiral ladder. At best, you get a two-pixel wide spiral with rungs that are far too small to see.

A 'scanning' electron microscope (SEM) can see individual atoms - but only under special circumstances - such as when they are in 'bulk' form. Picking out a single strand of DNA is not the kind of thing they do well.

So the answer is "No". Sorry! SteveBaker (talk) 18:53, 3 November 2008 (UTC)

What is happening here?

http://www.youtube.com/watch?v=EwKEGwAvQ54 http://www.youtube.com/watch?v=eNvZLTkj2kw

Calcium Bicarbonate does not exist in solid form, therefore these must be fake right? —Preceding unsigned comment added by 72.130.237.183 (talk) 07:18, 3 November 2008 (UTC)

Someone suggested their gelatine balls. Whatever the case, the person is either bullshitting or confused. Going by the comments, I'm really not sure but leaning towards bullshitting Nil Einne (talk) 10:54, 3 November 2008 (UTC)

Actually considering how many people are repeating the same thing, I'm guessing this is some sort of dumb joke aimed at people who don't know chemistry hoping to get them to waste time and make a fool of themselves by looking for calcium bicarbonate. The premise is nonsensical anyway. How can you claim they are water balls when you dumb so much crap into the water to get the balls? Nil Einne (talk) 13:18, 3 November 2008 (UTC)

Why do lovebirds cuddle up to each other?

Is it only the bird that they're in a relationship with that they cuddle up to or do lovebirds just like to get close to each other in general? --90.240.85.78 (talk) 08:18, 3 November 2008 (UTC)

Well, not clear but the article says, Lovebirds "are a social and affectionate small parrot," happy to preen their favourite (human) people and "the name Lovebird stems from these parrots' strong, monogamous pair bonding and the long periods of time in which paired birds will spend [sitting] beside one another." Small flocks a speciality too. So it looks like they are socially friendly but cuddly to close companions. Julia Rossi (talk) 10:42, 3 November 2008 (UTC)

Power 8

I have just come up with the term "Power 8" in Airbus article. I did not find any article regarding Power 8. What is meaning of power 8? Thank you--202.168.229.245 (talk) 09:28, 3 November 2008 (UTC)

According to Airbus#2007 restructuring it's Airbus's hip-sounding name for a plan to lay off thousands of workers and sell or close three plants. —Angr 09:49, 3 November 2008 (UTC)

Why do plants use chlorophyll?

Why do plants use chlorophyll which is a green pigment? Wouldn't it be more useful to use a red pigment so that red light, which is of a high wavelength and thus low energy, is the only light not used? Taking it further, couldn't they use a black pigment? Are there any reasons or theories for why chlorophyll is used? --RMFan1 (talk) 12:03, 3 November 2008 (UTC)

I think it's because of what wavelengths the sun is brightest at. I don't know the details. --Tango (talk) 12:22, 3 November 2008 (UTC)

With evolution it's always very difficult to answer 'why'. It could be just chance. Remember evolution doesn't have a set goal or intelligence. It doesn't know what's best. These speculations [8] [9] may interest you. This Yahoo answer [10] is rather good too IMHO. My gut feeling is it would be difficult for a pigment to absorb the entire spectrum (it's obviously possible but it's not so easy for it to happen by pure chance). Very likely, any change to absorb more in the green area would reduce absorption in the blue region which will likely make the plant less efficient. You could use a different pigment (and plants do have different pigments) but this adds another layer of complexity and cost to the plant (remember as well the pigment may compete against the existing pigments to some extent) so unless the tradeoff with having this new pigment makes up for itself, it's not likely to survive. But particularly if this new pigment arises late in the game, your existing pigments are already good enough that it's not easy for this new pigment to provide an advantage to the plant. Remember as well that you need to use the energy effectively, if your just absorbing it but not converting it to chemical energy you just end up with a hot plant. However this is just idle speculation, it's one of the many things we will probably never know why Nil Einne (talk) 13:08, 3 November 2008 (UTC)

You may also be interested in [11] which has the absorption spectra of various pigments Nil Einne (talk) 14:46, 3 November 2008 (UTC)

The photoelectric effect implies that chemical reactions involving light can't just use any frequency it likes. If the energy needed to liberate an electron equals say, the yellow wavelength, no amount of red light will do. Similarly, blue light might excite electrons at other places in the process that should not have been excited, ruining the chemical reaction. When taking efficiency of the process into account or what building blocks it requires, chlorophyll might come out on top. (Chlorophyll by the way comes in different types that absorbs different wavelengths) The issue is not settled though, according to [12] which speculates that chlorophyll might have been a historical accident from when algae competed against green-absorbing organisms in the ocean. EverGreg (talk) 14:03, 3 November 2008 (UTC)

earthworms

I want to now how does the earthworms eat? —Preceding unsigned comment added by 204.108.96.22 (talk) 15:59, 3 November 2008 (UTC)

Our article on earthworms has some sentances about this, in the "anatomy" section. There is also a bit in the section "Locomotion and importance to soil". Also, the earthworm article contains links to many more articles about specific families of Earthworms; there is may be more details in those articles if you do some snooping around... --Jayron32.talk.contribs 17:06, 3 November 2008 (UTC)

Preventing inbreeding among critically endangered animals

I read,via a featured yahoo article (here [13]), about the rare sighting and photographing of a Far Eastern Leopard (i.e., the Amur Leopard) wherein concern was expressed on the matter of probable genetic defects arising due to inbreeding among the critically low population of Amur leopards. What methods could/do the scientists use to prevent these defects when attempting to revive the population of a critically endangered species?--Leif edling (talk) 17:19, 3 November 2008 (UTC)

You could do selective breeding and perhaps some sort of 'genetic compatibility testing' (similar to the way Genetic testing is sometimes used to test for compatibility of couples in some small ethnic groups e.g. [14]). If you want to go ever further, you could use in vitro fertilisation coupled with preimplantation genetic diagnosis. Trouble is, these methods are rather labour intensive (particularly if the population is over a resonable large range) and require you to regularly interfere in the wild population (not something you want to do when there are few members left). In particular, the first method requires you to either intefere in mate choice somehow or to use artifical insemination (and hope other males, e.g. the female leopards well mate, don't kill the offspring or more successfully inseminate the female then you). The second method, presuming you don't want to subject the female to prolonged captivity, requires you to capture the female several times and hope the female doesn't get inseminated before you extract the unfertilised eggs (actually I wonder if you might have no choice but to hold the female, at least for a few days when she nears her period of fertility). Also, presuming you follow the system used in humans of using more embryons then would normally occur to increase the odds, you run the risk of killing the female unless you find a way to interfere in her giving birth if necessary (which carries its own risks). Even then, I suspect you'd still likely have low odds of success requiring you to repeat the process several times. Plus there's still the problem of how males will react (edit: I see from the article there are only 20-30 left in the wild, I presume then they are largely solitary, if the male mate doesn't hang around at all then this shouldn't be an issue). I've never heard of anyone seriously propose these methods except perhaps for breeding captive animals (perhaps for the eventual reintroduction into the wild). I believe the Chinese are doing some stuff with Pandas, but that's more about actually getting them to breed I think and only with ones in cativity. In any case, our best bet is to just prevent this happening in the first place (yes I know this doesn't help with the Amurs). Nil Einne (talk) 17:50, 3 November 2008 (UTC)

N.B. These problems will be lessened somewhat if you capture and hold your subjects in captivity rather then allowing them to stay in the wild, but this brings its own problems and is likely to be extremely controversial. Also, I read in the Amur Leopard article that there are existing Amur leopards in captivity and these would likely already be selectively bred but I doubt there's much support for bringing any of the wild specimens into play. The only (remote) possibility IMHO is males could be tranquilised and sperm samples taken and this used with the ones already in captivity. Nil Einne (talk) 17:54, 3 November 2008 (UTC)

Also, captive breeding programs can introduce problems when there is TOO much "genetic diversity" in the breeding population. C.f. orangutans. Early captive breeding programs focused on genetic diversity by interbreeding different populations of orangutan; later genetic studies showed that these populations were likely seperate species, so it called into question the viability of the "crossbreed" orangutans; the different populations were likely different enough to be uniquely adapted to their seperate environments, and it was determined that releasing the hybrid orangutans back into the wild was too risky. The population of orangs at the National Zoo in Washington, D.C. consist of these hybrids; they are currently part of the National Zoo's primate language lab... --Jayron32.talk.contribs 02:17, 4 November 2008 (UTC)

Is there a difference between emperical evidence and observational evidence?

Is there a difference between emperical evidence and observational evidence or can these terms be used interchangeably? 216.239.234.196 (talk) 18:25, 3 November 2008 (UTC)

I'd say they were interchangeable. --Tango (talk) 18:29, 3 November 2008 (UTC)

Empirical evidence: "evidence acquired through direct observation, preferably under controlled circumstances, with results reported in well-defined units of measure" Sounds pretty synonymous with observation to me. —Cyclonenim (talk · contribs · email) 19:54, 3 November 2008 (UTC)

THC effect on blood donation?

I smoke Marijuana daily. After voting tomorrow, I intend to give blood. Will the THC in my blood cause my donation to be discarded? --Unshelled Peanuts (talk) 18:30, 3 November 2008 (UTC)

In some countries, you are told not to give blood if you take illegal drugs, even those that are smoked or taken orally. If you take such drugs nasally or intravenously, most countries will have rules that say you shouldn't donate blood. I'm not aware of any country where blood centers test the blood for THC or other drugs. --NorwegianBlue ^talk 19:02, 3 November 2008 (UTC)

This says it's acceptable, at this particular institution, "as long as you are not under the influence of marijuana at the time of donation". It may well vary at other centres both nationally and internationally. —Cyclonenim (talk · contribs · email) 19:04, 3 November 2008 (UTC)

Some people's blood is thrown out automatically anyway, even if they don't take drugs. —Angr 19:09, 3 November 2008 (UTC)

How is that relevent to the question? It'll probably just spark debate. —Cyclonenim (talk · contribs · email) 19:13, 3 November 2008 (UTC)

I am quitely pondering the contact high for the guy who receives this blood later on... For some reason, the idea is mildly amusing to me... --Jayron32.talk.contribs 19:42, 3 November 2008 (UTC)

Not as inexplicably mildly amusing as the recipient would find:) DMacks (talk) 01:57, 4 November 2008 (UTC)

Maybe I had a blood transfusion recently... Maybe that explains my mild amusement... --Jayron32.talk.contribs 02:05, 4 November 2008 (UTC)

It might also explain forgetting that you had a transfusion recently. —Tamfang (talk) 04:35, 4 November 2008 (UTC)

Generally, though, if the blood bank doesn't ask a question about illicit drug use in general (not specifically IV drugs), they didn't care about it in the first place and won't throw out the blood. THC and marijuana consumption are not considered to be "of interest" for blood safety, the only drugs that are always a concern are IV ones (since that's an infection route for HIV and hepatitis). Some blood banks have stricter policies, but they're not recommended (at least by any guidelines I've seen). If you're too stoned to give a straight answer or remember what else you might have done, that might be a problem, but the same is true for alcohol. SDY (talk) 22:37, 4 November 2008 (UTC)

Why Earth's rotation slows down?

I was just reading about how leap seconds are added to the UTC time because Earth's rotation is slowing down. Has this been happening since the Big Bang or does it increase and decrease in cycles? If not a cycle, wouldn't Earth eventually stop rotating? Elfalem (talk) 20:16, 3 November 2008 (UTC)

Currently the spin rate changes due to friction of tides. The angular momentum is transferred to the moon. This slowing probably started when the moon was created and would have been happening ever since. The Moon would once have been much closer to the earth, with a day only lasting a few hours. Eventually when the day is as long as a lunar month the moon and earth will be tidally locked and there will be no more effect from this. The sun however also causes tides that slows down the earth's spin too. Graeme Bartlett (talk) 20:40, 3 November 2008 (UTC)

As for "stop rotating", it depends on what your frame of reference is. Consider the moon which, being tidally locked, is a useful illustration of what Earth would eventually act like. To an Earth-bound observer, the moon appears not to rotate (only one face is ever shown). However, if you were to take an extraterrestrial top-down viewpoint, you'd see that the moon actually has one rotation per orbital revolution. The Earth is likewise moving towards such an end state. — Lomn 20:54, 3 November 2008 (UTC)

Actually, I think most of the slowdown is due to post-glacial rebound, the land that was weighed down by glaciers is rebounding which moves mass away from the centre of rotation. Just like putting your arms out while spinning on the spot, that slows down the rotation. Tidal friction does slow the Earth's rotation, but very slowly. --Tango (talk) 21:22, 3 November 2008 (UTC)

I've done some calculations (feel free to check my maths) - the current rate of slowing is around 1.7ms per century. Even rounding to to 2ms per century in the approx 5 billion years life of the Sun the earth will only have lost just over 50% of it's rotational speed (my calculations give a result of a day of 52 hours or so) - so no, the earth will not 'stop' rotating in it's lifetime - it will be swallowed by the Sun before that. Exxolon (talk) 00:08, 4 November 2008 (UTC)

Hmm - further calculations. Currently the earth takes 86,400 seconds to rotate one revolution. At the 1.7ms slowdown per century my calculations indicate it will take over 5 TRILLION years for the earth to stop rotating. Exxolon (talk) 14:15, 4 November 2008 (UTC)

Leap-seconds are subtle. We don't need them because "earth is slowing down." We need them because earth has alraedy slowed down since the date at which we defined the second. If the earth were to suddenly quit slowing down and remain at its current rotational rate, we would still need leap seconds: as a clock, earth is running a bit slow. To keep in sync, we need about one leap second every 18 months. Since earth continues to slow down, leap seconds will become more frequent. -Arch dude (talk) 14:46, 4 November 2008 (UTC)

The universe is 13.8 billion years old. The Earth is 4.5 billion years old. I think it's safe to say that the Earth has not been slowing down since the big bang. — DanielLC 16:21, 4 November 2008 (UTC)

Are there any legitimate scientific alternatives to evolution?

Are there any legitimate alternative scientific explanations to evolution? For example, for the causes of global warming, solar variation is a legitimate alternative scientific hypothesis. Are there anything similar alternatives to evolution? 216.239.234.196 (talk) 20:48, 3 November 2008 (UTC)

I don't like to respond to one question by asking another but I think it important in this case to ask: What do you mean by "legitimate?

For example, do you mean:

• It seemed plausible when first considered, but did not stand up to serious scrutiny?

• It seems plausible even after serious consideration, but has been shown to be incorrect?

• It is a thoroughly "respectable" theory that has not been disproven, and provides as good an explanation of the known facts?

CBHA (talk) 21:25, 3 November 2008 (UTC)

The question is akin to asking "Are there any legitimate alternative scientific explanations to the motion of the sun in the sky?" Sure, at one point in history, people believed that the sun moved around the earth. Evolution is such a basic concept, it is no less accepted than is the heliocentric solar system is. --Jayron32.talk.contribs 21:31, 3 November 2008 (UTC)

A key point to make about evolution is that it isn't just a way of explaining observations, it's a logical consequence of life as we know it. If you have lifeforms that reproduce in a way that has a possibility of random mutations (which we do, there's no real doubt about that bit), then evolution is going to happen, it's obvious. The only question is whether or not evolution is sufficient to explain the variety and complexity of the lifeforms we observe. As for alternative answers to that question, I've never heard of any that would qualify as scientific (ie. falsifiable, fit observations and aren't so extremely complicated and unlikely that Occam's Razor rejects them without a second thought). --Tango (talk) 21:32, 3 November 2008 (UTC)

(I'm the OP on a different PC) If it helps, if you look the global warming article, it states:

"Some other hypotheses departing from the consensus view have been suggested to explain most of the temperature increase. One such hypothesis proposes that warming may be the result of variations in solar activity."

http://en.wikipedia.org/wiki/Global_warming#Solar_variation

I'm just wondering if there are any competing explanations to evolution, even if not accepted by the consensus of current scientists. 67.184.14.87 (talk) 22:40, 3 November 2008 (UTC)

I'm pretty sure the answer is "no". There are variations on the theory, but I don't think anyone has suggested anything significantly different that is actually based on science. --Tango (talk) 22:47, 3 November 2008 (UTC)

It depends on how you define evolution. Lamarckism is a form of evolution, but it is very different from Darwin's inheritance with variation/survival of the fittest. It's also thoroughly refuted (but, in a certain sense, nice - if you father worked out, you get to be stronger ;-). But no, in modern biology there is no competing theory to evolution, and I'd expect that all new theories would be refinements, not replacements, of evolution. --Stephan Schulz (talk) 23:03, 3 November 2008 (UTC)

Let's put it this way. There is a lot of variety to life on earth and a fossil record which seems to imply some sort of shared descent. The best scientific explanation of that is some form of evolution—currently evolution by natural selection as articulated by the modern synthesis is the chief candidate for that, but that is relatively recent (1930s; before that Darwinism was thought to have been a dead-end when it comes to the specific mechanism of evolution). Are there other explanations? The only two that any people have put out is some form of special creation (a supernaturalistic intervention) or that extraterrestrials have somehow seeded the planet and manipulated the gene pool (a naturalistic invention). Neither of these theories are scientific as neither are testable, though one could imagine a world in which the latter became possible to test (aliens arrive, thank us for all the hard work). --98.217.8.46 (talk) 02:00, 4 November 2008 (UTC)

Once you get your head around evolution - you rapidly realise that there is no way it cannot happen. If there is:

• Occasional variation in the genetic makeup of individuals...
• ...that is passed on from parent to child organism...
• ...and which influences the ability of the organism to produce offspring...
• ...then there is no way for there NOT to be evolution.

Since all of those things are demonstrably true - then there simply MUST be evolutionary change. The only questions for which an alternative theory might be postulated is whether evolution actually accounts for all of the variation we see - (it seems that it does) and whether it provides some kind of mechanism for how life appeared from non-living things (maybe...maybe not...the jury is still out on that one). But there can't be reasonable doubt about whether things evolve - it's really simple to demonstrate in a laboratory - it happens every day with things like drug-resistant diseases and rats that become immune to rat poison. Now that we've recognised the mechanism happening in life-forms, we can now see it appearing in other settings - the idea that 'memes' are evolving ideas that pass from brain to brain along various communications channels - changing as that happens is an interesting variation on the idea. I would argue that the current financial crisis is the consequence of businesses evolving more and more tightly tuned business practices over the course of time without the pressure of legal limitations to force them to evolve in ways we'd like. You can even argue that (for example) dogs have "evolved" to be suitable pets for humans because our selective breeding of them is merely another influence on their ability to reproduce. It doesn't matter whether aliens manipulated our genes - the aliens had to have evolved at some point (or the meta-aliens who created the aliens...or...). Even if creationism/intelligent-design (a seriously whacked-out theory if ever there was one) turned out to be true - evolution must ALSO be true - because we can see it in action - we can make it happen whenever we choose to do so - and it behaves as we would predict it should when we do those experiments. Hence creationism/ID could only ever be a supplement to the theory of evolution - it can't replace it. SteveBaker (talk) 05:14, 4 November 2008 (UTC)

You may compare the situation to physics. We have Einsteins theory of gravitation and then there's legitimate alternative theories on gravitation. But there's no alternative to gravitation. In biology there's lots of theories that go beyond school-book texts on evolution and some of them even conflict between each other, such as, genetic drift, Terry Deacons ideas about the Bengalese finch, the theory of punctuated equilibrium, even an almost-lamarckism theory on how certain traits are being transferred, but all of these incorporate darwin's theories. This is a common situation in science, compare for instance with how Newton's laws of gravity is included in Einstein's theory. EverGreg (talk) 09:20, 4 November 2008 (UTC)

These misunderstandings mainly come from two different definitions of the word theory. In common language, people use the word "theory" to mean what scientsists call a "hypothesis", which is an as-yet-untested idea (Like "I have a theory about why so-and-so happens.."). The deal is, this is NOT AT ALL what a scientific theory is. A scientific theory is best desribed as a productive framework of ideas. By productive, it means you can work within it and remain both logically and observationally consistant. To put it in another way, a theory is a logical explanation which provides a framework for understanding various related observations. So we have Atomic theory which contains all we know about the atom, from a chemists framework. It isn't that there are alternatives to Atomic Theory seriously being considered; it is a widely accepted framework of ideas, and chemists can do productive work within it. Atomic theory is constantly being modified by new discoveries, but as a coherant realm of thought it is quite solid and useful. Evolution theory is no less a complete and productive framework of thought... --Jayron32.talk.contribs 18:46, 4 November 2008 (UTC)

That's why I used the word 'explanation' in the OP. 216.239.234.196 (talk) 19:52, 4 November 2008 (UTC)

Mesoscaphe

The noted oceanographer and submersible designer Jacques Piccard recently passed away. In the Wikipedia article on him he is credited with the design of the bathyscaphe Trieste. He is also credited with the design of the mesoscaphe Ben Franklin (PX-15) and commanded the mission in 1969. There is no reference or link to "mesoscaphe" in Wikipedia. What is a "mesoscaphe" and how is it difference from a bathyscaphe? Garybirk (talk) 20:58, 3 November 2008 (UTC)

One would assume that the mesoscaphe was so called because it was designed for exploration at levels not as deep as those reachable by a bathyscaphe. Bathy- comes from the Greek word for "deep"; meso- from the Greek word for "middle." Deor (talk) 23:10, 3 November 2008 (UTC)

Imaginary helium balloon

If you had an imaginary balloon and tied it to a small car, about how many cubic feet of helium would you need to fill it with to make the car float? Louis Waweru  Talk  21:48, 3 November 2008 (UTC)

I don't know any way of working this out, but for some reason I imagine even if you filled the whole car with helium, it would not lift. I imagine the mass of the car is too great. —Cyclonenim (talk · contribs · email) 21:49, 3 November 2008 (UTC)

Helium, at standard temperature and pressure, has a density of 0.1786 g/L. The density of air (again at STP) is 1.2754 g/L. Consequently, you get about 1.1 grams of lift per liter of helium. Assuming a 1000kg car, you'd need about 900 000 liters of helium -- a spherical balloon some 12 meters in diameter (and that's ignoring the mass of the balloon and other associated hardware). — Lomn 21:56, 3 November 2008 (UTC)

Thank you for the grams/liters number. This was a very nice answer. Louis Waweru  Talk  22:12, 3 November 2008 (UTC)

Google says 12 meters isn't enough..

733 (meters^3) = 733 000 liters

4/3 pi r^3 right? 71.176.167.123 (talk) 23:54, 3 November 2008 (UTC)

FYI, what you typed rendered as 4/(3pi)*12^3 -- pi is on the wrong side of 4/3, and you cubed the diameter rather than the radius. — Lomn 14:23, 4 November 2008 (UTC)

Are you sure you typed the numbers in right? I get 905 m³. --Tango (talk) 00:04, 4 November 2008 (UTC)

That was just an estimate. A spherical 900,000 liter volume is about 12 m diameter. So is 905 m³ ~Amatulić (talk) 00:06, 4 November 2008 (UTC)\

So if you want to REALLY be sure to do it, just make the balloon 12.5 meters. BTW, the calculation can be seen empirically with such objects as blimps. Compare the size of the balloon to the size of the car it is carrying. I am sure that the balloon in a blimp is more than adequate (i.e. its SO big that it contains MUCH more helium than needed) but it does give you an idea of scale... --Jayron32.talk.contribs 03:49, 4 November 2008 (UTC)

905 is greater than 900, so 12 meters already has a margin of error. The blimps can't contain too much extra helium, otherwise they would just float up - all the extra helium has to be balanced by extra ballast (which can be dumped in an emergency to gain more lift - they'll certainly have some ballast, but I'm not how much is typical). --Tango (talk) 19:18, 4 November 2008 (UTC)

That's at STP, the helium is under compression from the balloon so it will take an even larger diameter. -- Mad031683 (talk) 18:09, 4 November 2008 (UTC)

The depends what kind of balloon you have. Helium party balloons are often made of foil (stops them going flat as fast, I think - presumably helium, being smaller than oxygen and nitrogen, gets through the holes in rubber faster) which isn't very elastic at all so there is virtually no compression. I'm not really sure what blimps, etc., are made of, but I doubt they involve much compression. --Tango (talk) 19:18, 4 November 2008 (UTC)

Imaginary balloons aren't very good at holding helium ;) 137.108.145.10 (talk) 14:18, 5 November 2008 (UTC)

observing the dead cat

Forgive me if I'm interpreting this wrong.. The article says the cat "is placed in a sealed box shielded against environmentally induced quantum decoherence".. but isn't the question moot because it's impossible to shield against quantum decoherence? If the cat dies then its mass is concentrated closer to the bottom of the box than if it were standing up.. so light will gravitationally lens around the box slightly differently.. 71.176.167.123 (talk) 22:52, 3 November 2008 (UTC)

That's why it is a thought experiment. The cat is perfectly spherical, of uniform density, and the box is in free fall ;-). --Stephan Schulz (talk) 23:05, 3 November 2008 (UTC)

That's an interesting introduction bringing gravity into the problem. If there was a proper theory that combined quantum mechanics and gravitation then one would probably be able to have a superposition where he mass was at the bottom and where the mass was in the middle. I don't think it works out very well at present though - have to hand over to someone who knows more about that. (An applied mathematician considering milk production: consider a spherical cow...) Dmcq (talk) 23:08, 3 November 2008 (UTC)

Schrödinger's cat, like many thought experiments, involve assumptions to get the point across. Maxwell's demon, for example, assumes the existence of a massless door that requires no energy to open and close. You do have a novel way of determining the position of the cat through gravitational lensing, but this still tells you nothing about the living state, only whether the cat is standing up or lying down. For the purpose of this experiment, assume the box is too cramped for the cat to move. ~Amatulić (talk) 23:11, 3 November 2008 (UTC)

See Spherical cow. The origin of the term is supposed to be that people from agriculture went to someone from the physics department at the University of Illinois to see if the folks there could help with a problem of decreasing milk production [15]. Edison (talk) 04:02, 4 November 2008 (UTC)

Essentially, if you put the 50% killing mechanism and a cat, into an impossible magic box. Something impossible happens to the cat. Perhaps not as shocking as Schrodinger meant it to be, but it's still useful as a thought experiment and teaching tool. APL (talk) 14:07, 4 November 2008 (UTC)

I remember reading an article on here where they pointed out that a small gravitational effect can be masked by the quantum effects on the scale, or something to that effect. I doubt it would do much at that scale, but that's only one of the reasons the quantum waveform would collapse if this thought experiment were actually carried out. — DanielLC 16:14, 4 November 2008 (UTC)

Personally - I've always felt that that thought experiment doesn't go far enough. Consider that the experimenter and his wife start the day together. The experimenter goes into completely enclosed lab and starts the cat experiment. At the end of the day, he plans to phone home and chat with his wife to tell her how his day went. He's a sensitive fellow and is rather fond of cats - so while he doesn't know whether the cat is alive or dead, he's in a simple, single state of not knowing. But when he opens the box to discover what happened...far from the quantum state of the cat changing - HIS state changes. He is now in an entangled state between being happy that the cat is OK - or being devastated that it died. Not until he phones home does his state become coherent The enclosed box with the cat inside that is either dead or not dead depending on whether an atom decayed or not - is completely analogous to the experimenter inside the sealed lab with either a dead or live cat that makes him either sad or happy...his happiness state is just as much determined by that single atomic-scale event as is the cat's morbidity...except that there is a longer delay before it happens to him. However, we may argue that when he phones home, all he's REALLY doing is pulling his wife and the telephone lines between them into the same entanglement as the cat and the atom. It's not unreasonable to imagine ripples of entanglement spreading outwards to other parts of the planet and eventually, to the entire universe. The fact that the position of the cat in the box causes gravitational disturbances simply means that the entanglement spread out at the speed of light - rather than at the speed that the researcher would call his wife...it's no different in principle. This is the most powerful argument for the 'many worlds' interpretation IMHO. SteveBaker (talk) 20:37, 4 November 2008 (UTC)

That is an interpretation I've heard before. I think "observation" is roughly defined, in that interpretation, as something sufficient to trigger that rapid expansion of the entanglement (presumably speed of light, or marginally slower). --Tango (talk) 00:37, 5 November 2008 (UTC)

I don't really see that supporting the many worlds theory. It seems more like a matter of frame of reference. If you're the researcher before he opens the box or the wife before he phones home, the state of the cat is undefined; it IS either alive or dead to an observer inside the box/lab, but for the researcher/wife the universe from their frame of reference is not a function of the state of the cat. 71.176.167.123 (talk) 16:45, 5 November 2008 (UTC)

I see it as supporting many worlds as follows: If the entanglement spreads out when "observed" (to include the observer into the entanglement) rather than "collapsing" as so often explained - then eventually, the entire universe is in a state of entanglement with the cat's demise/survival causing different consequences for each state. The scientist is so upset at the death of the cat that he commits suicide, he never invents the magic CO2 absorbing substance that would have saved the world from global warming. The scientist finds the cat is alive and is inspired to go on to save the world. So the entire planet is in superposition between being globally warmed or not. This effect can spread - much like the "butterfly effect" to result in all of everything being in superposition based on that one atom either decaying or not. Since two completely separate versions of the universe are now "superimposed" with no way for one to influence the other - we now have two parallel universes. In reality, every atomic decay or other random quantum event causes the universe to be in an entangled state - and that entanglement can only (it seems) spread outwards at something like the speed of light. So for all PRACTICAL purposes, you have parallel worlds. The only way to avoid that is with the idea that "observing" causes a collapse of the entanglement. That's OK when it's a cat in a box - but if you'll allow me to push the thought experiment out to being an entire planet that's either entangled - then I think you have many-worlds whether you like it or not. SteveBaker (talk) 20:18, 5 November 2008 (UTC)